1. Field of the Invention
The invention relates to a film magazine, and more particularly to a motion picture camera film magazine which can accommodate movement of the camera without thereafter having to rethread the film.
2. Description of the Prior Art
Normally a camera is fixed to the film magazine with which it is associated. Consequently the camera can be moved without affecting the threading of the film in the camera. However, in certain installations the magazine is fixed in position and it is necessary on occasion to move the camera relative to the magazine.
For example, when filming is done from an aircraft, the film magazine and the camera and its associated lens are often mounted in a spherical housing to protect them from wind or rapid air movement damage. The size of the housing is made as small as possible to minimize air drag and stress on the aircraft.
One such installation is described in my copending patent application Ser. No. 07/794,000 filed Nov. 18, 1991, and entitled "Gyroscopically Stabilized Apparatus". A motion picture camera is supported upon a platform which is fixed to an internal wall of a spherical housing adapted to be mounted to a helicopter. A film magazine is mounted on top of the camera, with the feed and take up reels in longitudinal alignment.
An opening or window is provided in the housing adjacent the camera lens, and the lens is located as close to this window as possible to provide wide angle coverage of the target object. A zoom or variable focal length lens is generally used, and its comparatively long length necessitates placement of the camera at the rear of the housing.
Sometimes it is desirable in a filming sequence to use a shorter, fixed focal length lens. In the prior art this was done by installing a series of spacers between the magazine and the camera to locate the shorter lens closer to the housing window. This is a painstaking operation which takes time, and it also requires rethreading of the film in the new camera position. Alternatively, the housing could be made large enough to allow both the magazine and the camera to be moved back and forth without affecting the film threading but, as previously indicated, this would undesirably increase the size of the housing and its frontal area, and impose a correspondingly increased stress on the aircraft.
In gyroscopically stabilized camera systems such as that disclosed in my copending patent application, it is important that the weight of the various components be balanced about the various axes of pivotal movement. Relatively complex means have been used to compensate for the change in weight balance occasioned when film passes from the supply reel of a magazine to an in-line or longitudinally aligned take up reel. Typically, a small weight was provided and its position incrementally changed according to the weight imbalance.
Another weight compensation arrangement is disclosed in U.S. Pat. No. 4,826,310 issued May 2, 1989 for "Constant Center of Gravity Film Camera Magazine". The disclosed system includes feed and take up spindles mounted on a carriage whose position is changed to the extent necessary to maintain a fixed center of gravity for the magazine during movement of film between the spindles. Movement of the carriages introduces a considerable degree of complexity to the arrangement.
Certain prior art arrangement of a camera and a magazine within a housing are also wasteful of space because the feed and take up reels are lined up behind one another. Such an arrangement limits the diameter and film capacity of the reels because they have to fit between the front and rear of the protective housing. Side-by-side reels and means for laterally feeding film between the reels is known, but suitable arrangements enclosed within a protective spherical housing of the type mentioned above are not available.